For the remainder of this book, let me introduce a new example
that is less complex than Groucho Marx University, and may be closer
to the tasks you will actually encounter. Consider the Virtual
Brewery, a small company that brews, as the name indicates, virtual
beer. To manage their business more efficiently, the virtual brewers
want to network their computers, which all happen to be PCs running
a bright and shiny 1.0.

On the same floor, just across the hall, there's the Virtual Winery,
who work closely with the brewery. They run an Ethernet of their own.
Quite naturally, the two companies want to link their networks once
they are operational. As a first step, they want to set up a gateway
host that forwards datagrams between the two subnets. Later, they also
want to have a UUCP link to the outside world, through which they
exchange mail and news. In the long run, the also want to set up a
SLIP connection to connect to the Internet occasionally.